When a patient has had knee surgery, especially knee replacement surgery, suggested exercises for improving the range of motion of the knee include extending and bending the knee over and over again. After surgery, the knee joint is stiff and painful to move. The joint will remain stiff until such exercises are performed regularly. Common knee exercises include performing isometric exercises consisting of manually moving the limb to be treated, while performing thrusts or counter thrusts in order to force the muscles of the limb to work and thus restore their initial flexibility, shape and quality. Exercises including flexing of the joint can give good results. However, this method of recuperation suffers from the major drawback of requiring action by a practitioner, e.g. a physiotherapist, whose professional qualifications are not essential for performing this work. A preferred exercise aid would allow a patient to exercise on his own and the patient should be able to easily and accurately measure improvement of joint motion, strength and flexibility.
Slow, continuous flexing of a joint, such as the knee, following surgery on that joint will promote rapid healing, reduce pain during healing and result in an increased range of motion of the joint. Devices for the continuous passive exercising of limbs for therapy, rehabilitation or healing often include a frame which cradles the leg within it, while the frame is driven slowly up and down with an electric motor and drive screw. This has caused difficulty as it is sometimes preferable to have the leg in a near horizontal position when it is straight. Setting and controlling the angle of flex is difficult with a frame type device.